Small molecule gas storage adapter

ABSTRACT

Various embodiments are generally directed to a casing connected to a top cap structure that consists of an adapter flange extending to an adapter barrel that is configured to fit wholly within the casing. The adapter barrel can be separated from the casing by an annulus that is filled to a predetermined annulus pressure while an internal chamber defined by the adapter barrel contains a gas having a small molecular size at a storage pressure that is greater than the predetermined annulus pressure.

SUMMARY

A casing, in accordance with various embodiments, is adapted for storage of gas with small molecular size by being connected to a top cap structure that consists of an adapter flange extending to an adapter barrel that is configured to fit wholly within the casing. The adapter barrel is separated from the casing by an annulus that is filled to a predetermined annulus pressure while an internal chamber defined by the adapter barrel contains a gas having a small molecular size at a storage pressure that is greater than the predetermined annulus pressure.

An adapter, in other embodiments, is utilized by forming a gas tight metal-to-metal seal by attaching a collar of a top cap structure to a casing prior to positioning an adapter barrel over the casing. The adapter barrel is pumped into the casing until an adapter flange that extends from the adapter barrel to contact the collar and form a sealed annulus between the adapter barrel and the casing. The annulus is filled with a material having low compressibility before the annulus is capped at a predetermined annulus pressure. An internal chamber of the adapter barrel is filled with a gas having a small molecular size to a storage pressure. The internal chamber is drained and experiences a drop from the storage pressure and subsequently is refilled with the gas and pressurized to the storage pressure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 represents portions of an example gas storage system in which various embodiments may be practiced.

FIG. 2 depicts a line representation of portions of an example gas storage container arranged in accordance with some embodiments.

FIG. 3 conveys a line representation of gas molecules that may be stored in the gas storage system in accordance with assorted embodiments.

FIGS. 4A-4C respectively illustrate portions of an example gas storage assembly that can be utilized in accordance with various embodiments.

FIG. 5 depicts portions of an example gas storage assembly configured and operated in accordance with some embodiments.

FIG. 6 is an example gas storage assembly installation routine that can be executed with the various embodiments of FIGS. 1-5.

DETAILED DESCRIPTION

Embodiments of a gas storage assembly generally utilize an adapter to securely seal a casing to entrap small molecule gas, such as hydrogen, helium, and neon.

The volume of gases consumed for personal, commercial, and industrial purposes has increased over time and appears to continue to grow. The storage of fluids and some gases can be safely facilitated with a variety of storage materials and configurations, such as metals, ceramics, stone, and polymers. However, the storage of relatively small gas molecules poses a difficult challenge for short-term, and long-term, time periods as leaks and/or gas permeation can occur despite the presence of materials and seals that effectively store large molecule gases. The presence of pressure can further exacerbate the difficulties of storing small molecule gas due to the molecular construction of storage tanks, containers, and seals.

With these issues in mind, an adapter constructed and utilized in accordance with various embodiments can safely store small molecule gas in a tank/container under dynamic pressure over extended periods of time. The use of an adapter that safely stores small molecular gasses allows a tank/container that is suitable for storing large molecule gases to store gasses of nearly any molecular size. Efficient installation and utilization of a tank/container adapter to store gases with small molecule sizes under pressure allows older generation large molecule gas storage to be repurposed with minimal labor, time, and cost.

FIG. 1 depicts portions of an example gas storage system 100 arranged with a subterranean gas storage container 102 and a gas storage tank 104. It is noted that a container is meant to be positioned partially, or completely, under a ground level (GL) while a tank is meant to be positioned wholly above the ground level. As shown, the gas storage container 102 is arranged to be wholly underground and continuously extending to a depth (D) into one or more subterranean formations.

The gas storage container 102 consists of at least one casing 106 that is sealed on the bottom 108 by a plug 110 and on the top 112 by a cap assembly 114. It is contemplated that multiple lengths of separate casing 106 are joined together to form the gas storage container 102 and extend to the predetermined depth, such as 50 feet or more, to allow gas storage under static, or dynamic, pressure, such as greater than 100 psi. The gas storage container 102 can have one or more ports 116 that allow piping/tubing to move gas into, and out of, the casing 106.

The gas storage tank 104 may be constructed of any type, number, and size of materials that form a sealed volume 118 accessed by gas transmission lines 120 to allow ingress, pressurization, and egress of various volumes of gas over time. Although the container 102 and tank 104 are not displayed with gauges, valves, and safety relief equipment, it is contemplated that the respective components 102/104 can be configured with one or more gas regulating, controlling, moving, pressurizing, and/or safety equipment. It is noted that the movement, pressurization, and storage of gas in the respective components 102/104 can be initiated, terminated, and controlled by one or more users positioned on site, which can be characterized as physically present with the components 102/104, or off site, which can be characterized as connected to the respective components 102/104 electronically.

FIG. 2 depicts a line representation of portions of an example gas storage container 130 that may be used as part of a gas storage system in combination with one or more other gas storage components. The gas storage container 130 defines a storage volume 132 defined by the interior, sealed aspect of the casing 106. A bottom plug 110, or bottom cap assembly 134, can establish a bottom container extent while a top cap structure 136 establishes a top container extent that provides gas transmission and pressurization.

While the materials and sealing components outlined in FIG. 2 are fully capable of storing conventional gases as well as small molecule gases, permeation into the materials by small molecule gases, such as Hydrogen, will accelerate fatigue through embrittlement and significantly shorten the service life of the storage. If embrittlement due to the storage of small molecule gas under pressure, such as above 1,000 psi, degrades the competency of the container 130 to the point of catastrophic failure, the release gas from a container 130 or from one or more locations about a container 130 can pose a serious hazard, particularly when flammable gases are being stored.

FIG. 3 displays molecular diagrams of assorted gases that can be stored in a gas storage container. An example molecule is H₂ 140, which has an atomic size and molecular configuration that is relatively small compared to other gases, such as methane 150 and ethane 160. Specifically, H₂ 140 has a length 142 and width 144 that defines a molecular area that is significantly smaller than the molecular area of methane 150, as defined by width 152 and height 154 measurements, or ethane 160, as defined by width 162 and height 164 measurements. While not drawn to scale, the molecules of FIG. 3 generally illustrate how storage of H₂ 140 can be more difficult than methane 150, ethane 160, or other natural gas hydrocarbons due to the relatively small size, particularly with regard to the material porosity of many gas storage casings, such as lead, steel, and iron.

Accordingly, various embodiments utilize an adapter to allow a typical casing 106, such as an oil well casing constructed of carbon steel or other steel alloys to be used to safely and reliably store gas with a relatively small molecular size, such as H₂. FIGS. 4A-4C respectively depict line representations of portions of an example gas storage container 170 configured and operated to store small molecule gas at relatively high pressures, such as over 1000 psi. The container utilizes a casing 106 that defines an interior volume along with a bottom plug or cap (not shown) and a top cap structure 172. The cap structure 172, in some embodiments, has a collar 174 that attaches to the casing 106 and presents a fastening surface 176 for an adapter flange 178 and lid 180.

FIG. 4A illustrates how the cap structure 172 fits together, once assembled, with the adapter flange 178 sandwiched between an upper portion 182 of the collar 174 and the lid 180. The enlarged size of the upper portion 182 allows one or more fasteners 184 to extend through the cap structure 174 to form a gas tight assembly that is accessed via one or more ports 116. The exploded view of FIG. 4B illustrates how the adapter flange 178 is connected to an adapter barrel 186 that defines an internal volume that is less than the volume of the outer casing 106. It is contemplated that the adapter barrel has a solid bottom that forms a water tight and air tight receptacle without installation of a plug, cap, lid, or cover onto the bottom of the barrel 186, opposite the flange 178.

While not limiting, various embodiments construct the adapter flange 178 and barrel 186 of forged, cast, machined, or assembled material, such as aluminum, which exhibits low permeability to small molecules, such as H₂ and high resistance to embrittlement, which extends the life of the adapter. It is contemplated that some, or all, of the adapter 178/186 can be coated with one or more materials to lower gas permeability even more and/or increase rigidity, corrosion resistance, and fatigue resistance. Some embodiments coat different aluminum adapters with a polymer, rubber, ceramic, or graphene material to allow a casing 106 to employ an uncoated adapter or one of various adapters that exhibit different operational characteristics due to the respective coatings.

The adapter 178/186 is configured for installation into a casing 106 without adjusting or removing the casing 106 from its position, whether partially or completely underground. It is contemplated that the adapter 178/186 can be utilized in above ground gas storage tanks. The size and shape of the adapter barrel 186 relative to the casing 106 produces an annulus 188 of empty space extending between the casing 106 and barrel 186 along the entirety of the barrel sidewalls 190. That is, an annulus 188 can be measured as the distance from an interior sidewall 192 of the casing 106 to a barrel sidewall 190. The annulus 188 allows the adapter barrel 186 to be installed, and removed, from the casing 106 without damaging the adapter barrel 186 and provides space for a damping material to be placed between the casing 106 and barrel 186.

In the close-up line representation of the annulus 188 in FIG. 4C, the threads 194 of the casing 106 are shown, which interact with matching threads of the collar 174 to mate a casing sealing surface 194 with the collar 174 via a metal-to-metal connection. In other words, the casing 106 is configured with threads 194 that flow into a tapered surface 196 that defines a sealing surface 196 that is brought into contact with the collar 174 to form a gas tight seal. While one or more sealing materials can be introduced between the collar 174 and casing 106, assorted embodiments machine the collar 174 and casing sealing surface 194 to tolerances that provide a gas and/or fluid tight seal strictly with a metal-to-metal connection.

FIG. 5 depicts a cross-sectional line representation of portions of an example gas storage container 210 arranged in accordance with various embodiments. The container 210 employs a casing 106 with first threads 194 positioned to secure a bottom cap 212 to a first region while second threads 194 secure a top cap 214 to a second region. It is noted that some embodiments utilize one or more plugs to seal a bottom of the casing 106 while other embodiments employ matching cap structures 212/214 that thread a collar onto the casing 106 and secure a lid onto the collar via fasteners, as illustrated in FIGS. 4A-4C.

Although the cap structures 212/214 may having matching configurations, the cap structure 212/214 located at the top portion of the casing 106 secures the adapter flange 178 between the collar 174 and lid 180 to ensure the adapter 178/186 does not inadvertently move or get ejected from the casing 106. The secure position of the adapter 178/186 defines the annulus 188. While the annulus 188 may be kept empty, or in a vacuum pressure differential, the cyclic filling and removing of gas within the adapter internal volume 216 can cause at least the adapter barrel 186 to expand and contract. Such barrel 186 movement can cause fatigue to the barrel 186 material as well as damage to the sidewalls of the casing 106 and/or barrel 186. Hence, some embodiments fill the annulus 188 with damping that reduces the expansion and contraction of the barrel 186 material in response to pressurization and depressurization of the internal volume 216.

The annulus 188, in various embodiments, is filled with a propylene glycol and brought to a constant pressure, such as 10 psi. Although other materials, and combinations of materials, can be used to fill the annulus 188, propylene glycol has an extremely low freezing point, low compressibility, and is compatible with corrosion inhibitors while being environmentally friendly. As the annulus 188 represents a finite and relatively uncompressible volume of glycol, pressure exerted on the barrel 186 is transferred to the outer casing 106 with minimal expansion of the barrel 186. As a result, fatigue and physical damage to the barrel 186 due to expansion and contraction of cyclic pressurizations are managed to meet, or exceed, the rate of deterioration due to embrittlement over time. The adapter and lid 180, in some embodiments, are sacrificial and are replaced according to a predetermined schedule that maintains a margin of safety for the container and extends the service life of the outer casing 106 and cap assemblies indefinitely.

While the adapter barrel 186 fits inside the casing 106, the vacuum pressure of the annulus 188 and bottom of the casing 106 can make removal difficult. To accommodate a more efficient removal, the annulus 188 is plumbed to one or more fill ports 218 that can be positioned in a bottom cap structure 172, as shown, or other locations that provide access to the annulus 188 from outside the casing 106. It is noted that positioning the fill port 218 at the bottom-most extent of the annulus 188, casing 106, and container 210 allows the annulus to be efficiently filled and drained with liquid, as opposed to a side positioned port that would potentially not drain some annulus liquid without high pressure. The annulus fill port 218 is connected to at least one feed line 220 that allows for the ingress, egress, and pressurization of the gas/fluid with respect to the annulus 188.

The annulus fill port 218 can be complemented by one or more annulus monitor port 222 that may be positioned anywhere on the casing 106, but in some embodiments extends through a top collar 174, as shown in FIG. 5. A bleed line 224 allows pressure, gas, and/or fluid to be released upon selection of a valve 226. The bleed line 224 further allows one or more gauges 228 to monitor conditions of the annulus 188, such as pressure, humidity, and temperature. Use of one or more ports 218/222 that access the annulus 188 allows the adapter 178/186 to be hydraulically pumped into position within the casing 106, which alleviates difficulties associated with purely mechanical, or pneumatic, adapter 178/186 installation.

For instance, incompressible fluid can be pumped into, and out of, the annulus 188 to draw the adapter 178/186 into, or out of, the casing 106. As a result, the annulus 188 can be used to aid adapter 178/186 installation and removal, which allows for different adapters 178/186 to be utilized for a container 210 over time to accommodate different gas storage conditions and capabilities. The monitoring of one or more annulus ports 218/222 provides data that can be used to determine the real-time current annulus gas/fluid condition. That is, pressure, and other environmental conditions in the annulus 188, can be tracked over time to calculate at least the volume, compressibility, density, and relative pressure of the gas/fluid in the annulus 188. Such annulus 188 conditions can be used to schedule proactive and/or reactive maintenance that serves to maintain the annulus 188 so that charging and discharging of gas in the adapter internal volume 216 does not induce more than minimal fatigue, corrosion, and mechanical war on the adapter 178/186.

Some embodiments utilize only metal-to-metal seals to create a gas, or fluid, tight enclosure with the container 210, as conveyed in FIG. 4C and shown by the casing/collar interactions 230 of FIG. 5. Other embodiments can complement metal-to-metal seals of the casing/collar with one or more metal or non-metal gaskets 232, such as cork, rubber, polymer, ceramic, and synthetic materials capable of sealing at working pressures. The use of one or more gaskets 232 in a cap structure 172 can be changed over time and allow the container 210 to provide optimal small molecule gas storage over a diverse range of temperatures and pressures.

FIG. 6 conveys a flowchart of an example adapter utilization routine 240 that can be executed with assorted embodiments of FIGS. 1-5 to provide gas storage for gases that have relatively small molecular size. The presence of a hollow, unfilled casing allows step 242 to begin the process of installing a single small molecule adapter into the casing. It is contemplated that the casing is constructed of a material, such as steel alloy, iron, or lead, that is not conducive to small molecule gas storage due to susceptibility to embrittlement. As such, the adapter can be constructed of a dissimilar material than the casing, such as aluminum, ceramics, and nanocomposites, that provides superior resistance to embrittlement than the casing.

Once the storage volume is depressurized and the lid 180 of the cap assembly is removed, the adapter is positioned over the hollow casing in step 242. Insertion of the adapter begins in step 244 and can involve using suction on the annular fill line 220 to pull the adapter into the casing until an adapter flange 178 contacts a cap structure collar 174, as illustrated in FIGS. 4A & 5. Once the adapter flange 178 is seated on the structure collar 174, the lid 180 is secured in place, which seals both the annulus 188 and the interior volume 216 of the adapter while isolating the annulus 188 from the interior volume 216.

The metal-to-metal seal may be complemented by one or more gaskets 232 positioned between the adapter flange, collar, and lid, The gas tight seal 230 and the gasket 232 between the collar 174 and the adapter flange 178 seal the annulus 188. The gasket 232 between the lid 180 and the adapter flange 178 seals the small molecule gas within the volume of the adapter 216 at pressures over 1000 psi.

With the annulus formed after the top cap structure has been assembled and secured so that the adapter flange is locked in place along with the adapter barrel, the volume of the annulus is displaced in step 248 by pumping a fluid or gas with low compressibility, such as propylene glycol down the annular fill line 220 and venting the volume of the annulus out the annular bleed valve 226. Once displaced, the bleed valve 226 is closed and the annulus is pressurized to a predetermined relative pressure, such as 10 psi, and the annulus drain/fill port is closed in step 250 and the annulus has a static condition until the adapter barrel expands and contracts to induce force and/or pressure on the annulus. It is noted that while the annulus drain/fill port remains closed during gas storage operations within the adapter barrel, the annulus monitor port can remain open to one or more gauges or be selectively opened with valving to allow at least annulus pressure to be detected.

Next, step 252 cyclically fills the internal chamber of the container, as defined by the adapter barrel, to a predetermined pressure and volume of gas before depressurizing the internal chamber as pressurized gas is released from the container. It is contemplated that the internal chamber is pressurized to a common pressure cyclically in step 252 or dynamic pressures are utilized over time depending on environmental conditions and/or desired amount of gas to be stored. Step 252 may be conducted for any amount of time with any number of gas fills/drains being conducted and associated with the internal chamber of the adapter barrel being pressurized and depressurized.

At any time, a user/operator of the container can evaluate in decision 254 to alter the annulus. If an annulus modification is in order, such as in response to a change in pressure of the annulus or a desire for a different compressibility value for the annulus, step 256 opens the annulus drain/fill port 220 and displaces the volume of the annulus out the bleed valve, which replaces the damping material of the annulus and repressurizing the annulus to different operating conditions. Some embodiments of step 256 simply fill and/or repressurize the annulus without displacing the annulus with new damping material/fluid. At the conclusion of the modification(s) to the annulus in step 256, the annulus is capped by returning to step 250.

In the event no annulus alteration is necessary from decision 254, the routine 240 returns to step 252 and the cyclical use of the internal chamber of the adapter barrel for the storage, and dispensing, of gas at a predetermined pressure, such as above 1000 psi. Through the use of the monitored and controlled annulus, along with the resistance to embrittlement of the adapter barrel compared to the outer casing, gas can be reliably stored and dispensed over time without material fatigue, corrosion, and leakage. The ability to interchange adapter barrels without modifying or moving an outer casing extends the service life of the container and allows for efficient alteration of the gas storage capabilities and performance of a gas storage container with minimal equipment and manpower. 

What is claimed is:
 1. An apparatus comprising casing connected to a top cap structure, the top cap structure comprising an adapter flange extending to an adapter barrel configured to fit wholly within the casing, the adapter barrel separated from the casing by an annulus filled to a predetermined pressure.
 2. The apparatus of claim 1, wherein the top cap structure comprises a collar threaded onto the casing to form a gas tight seal.
 3. The apparatus of claim 2, wherein the gas tight seal is a metal-to-meal physical connection.
 4. The apparatus of claim 1, wherein the annulus continuously extends around the adapter barrel between the casing and a bottom cap structure.
 5. The apparatus of claim 1, wherein the annulus is filled with propylene glycol.
 6. The apparatus of claim 5, wherein the annulus is maintained at a predetermined annulus pressure of 10 psi.
 7. The apparatus of claim 1, wherein a first gasket is positioned between the adapter flange and the collar.
 8. The apparatus of claim 7, wherein a second gasket is positioned between the adapter flange and a lid of the top cap structure.
 9. The apparatus of claim 8, wherein the lid comprises a fill port and a drain port each accessing an internal chamber defined by the adapter barrel.
 10. The apparatus of claim 1, wherein the annulus is accessed by a first port and a second port, the first port connected to a pressure gauge.
 11. The apparatus of claim 1, wherein the adapter barrel comprises only aluminum metal.
 12. The apparatus of claim 1, wherein an internal chamber of the adapter barrel stores hydrogen at a pressure above 1000 psi for longer than 1 week.
 13. A method comprising: forming a gas tight metal-to-metal seal by attaching a collar of a top cap structure to a casing; positioning an adapter barrel over the casing; pumping the adapter barrel into the casing until an adapter flange extending from the adapter barrel contacts the collar to form a sealed annulus between the adapter barrel and the casing; filling the annulus with a material having low compressibility; capping the annulus at a predetermined annulus pressure; filling an internal chamber with a gas having a small molecular size to a storage pressure, the internal chamber defined by the adapter barrel; draining a portion of the internal chamber, the internal chamber experiencing a drop from the storage pressure; and refilling the internal chamber to the storage pressure.
 14. The method of claim 13, wherein the predetermined annulus pressure is altered by selecting at least one valve connected to the annulus, but not the internal chamber of the adapter barrel.
 15. The method of claim 13, wherein the storage pressure remains for more than a week without adding pressure to the internal chamber.
 16. The method of claim 13, wherein the gas having a small molecular size is hydrogen.
 17. The method of claim 13, wherein the gas having a small molecular size is methane.
 18. The method of claim 13, wherein the casing and adapter barrel are constructed of different materials.
 19. The method of claim 13, wherein the adapter barrel is pumped into the casing with hydraulic fluid.
 20. The method of claim 13, wherein the adapter barrel is removed from the casing without moving or altering the casing. 